Tectonic setting of Middle Devonian to Lower Carboniferous rocks in the Magdalen Basin

Details

Tectonic setting of Middle Devonian to Lower Carboniferous rocks in the Magdalen Basin

Journal

Atlantic Geology

Author(s)

DurlingP., MarillierF.

ISSN-L

0843-5561

Publication state

Published

Issued date

1993

Peer-reviewed

Oui

Volume

29

Pages

199-217

Language

english

Abstract

Seismic reflection data in the Gulf of St. Lawrence were used to constructan isopach map of the Horton Group (Middle Devonian-Early Carboniferous)in the Magdalen Basin. The map shows that the Horton Group was depositedin basins that developed parallel to the offshore extension of structuraltrends in New Brunswick and the Gaspe Peninsula. Horton Group stratawere deposited in narrow linear fault bounded basins, presently upto 8 km deep, and in broad sag basins up to 3 km deep. The sag basinsmay thin latterally to form sedimentary veneers less than 1 km thick.The fault bounded basins are mostly half-grabens and they developedduring an early crustal extension phase. The largest and deepestbasin strikes northeast-southwest, almost parallel to the MonctonBasin in New Brunswick. Sag basins and thin veneers are not faultcontrolled and are widespread, underlying most of the Magdalen Basin.They probably formed later than the fault bounded basins in responseto the onset of a regional subsidence phase.Deformation of Horton Group rocks in the Magdalen Basin is concentratedin fault zones up to 20 km wide, and mainly affected deep subbasins,where thrust faults and possible flower structures are observed.An early deformation phase occurred towards the end of Horton Groupsedimentation (Late Tournaisian-Early Visean) and a later phase occurred,with less intensity, during the deposition of Visean to ?Namuriansediments. The first phase of deformation affected most of the MagdalenBasin, whereas the second phase affected mainly the southern areas.